Repeated technetium-99m pertechnetate scanning for children with obscure gastrointestinal bleeding.

From 1980 to 1992, we found false negative results from Technetium (Tc)-99m abdominal scans in seven children with massive gastrointestinal bleeding from ectopic gastric mucosae. Other examinations--including endoscopy, gastrointestinal series studies, angiography, and Tc-99m-labeled red blood cell scans to search for the source of the bleeding--were all in vain. Positive results were only obtained after repeated Tc-99m abdominal scans. Surgical specimens confirmed that ectopic gastric tissue was the source of bleeding in five patients with Meckel's diverticulum and two patients with enteric duplication.